This invention relates to a pump mechanism for dispensing small aliquots of a fluid, such as a biological reagent. It may serve as part of an apparatus which dispenses a plurality of reagents to be dispensed in small volumes.
Current methods for dispensing reagents generally use pumps which require the priming of tubing lines leading into and out of a pump. When the pumping is finished, the tubing lines must be flushed before a different reagent can be pumped, lest cross-contamination of reagents occur. Because of the need for priming and clearing tubing lines, such types of pumps are not easily interchangeable.
Pumping systems using a syringe housing ("syringe pumps") are well known to those in the field. The syringe is first filled with a liquid. The liquid can then be accurately dispensed by applying a precise pressure on the plunger, usually by an electromechanical actuator. The distance that the plunger is depressed directly controls the amount of fluid to be dispensed. Such syringe pumps have two advantages: 1) the absence of tubing lines leading into and out of a pump which must be primed and flushed, and 2) a separation of the wetted components from the electromechanical controlling elements.
Such syringe pumps are useful in situations where repetitive dispensing of precise amounts of liquid are required. A drawback of such syringe pumps is that interchanging syringes on a single electromechanical actuator requires that the actuator mechanism be realigned with the position of the syringe plunger that is being inserted. In circumstances where the syringes need to be changed often in order to change the dispensed reagent, the need for repetitive manual intervention to align the electromechanical actuator with the position of the syringe plunger is a disadvantage. This disadvantage will be more acutely felt in a dispensing instrument with many electromechanical actuators.